Method of and apparatus for bending the backing-up rolls of four-high rolling mills and the work rolls of two-high rolling mills

ABSTRACT

The invention relates to a rolling mill construction in which a roll is arranged to have pressure applied to the oppositely disposed end faces thereof through pressure-operated devices so that it may be bent about its longitudinal axis.

United States Patent 9 Inventor Lucien Diolot Neuilly, France Appl. No. 766,601 Filed Oct. 10, 1968 Patented Aug. 17, 1971 Assignee Societe Nouvelle Spidem Paris, France Priority Oct. 10, 1967 France METHOD OF AND APPARATUS FOR BENDING THE BACKING-UP ROLLS OF FOUR-HIGH ROLLING MILLS AND THE WORK ROLLS OF TWO-HIGH ROLLING MILLS Y 9 Claims, 3 Drawing Figs.

US. Cl Int. Cl

[50] Field of Search 72/245, 240, 237

[56] References Cited UNITED STATES PATENTS 2,611,150 9/1952 Goulding 72/245 3,364,715 l/1968 O'Brien 72/245 3,373,588 3/1968 Stone 72/237 3,461,705 8/1969 Neumann 72/243 Primary Examiner-Charles W. Lanham Assistant ExaminerB. J. Mustaikis Attorney-Edwin E. Greigg ABSTRACT: The invention relates to a rolling mill construction in which a roll is arranged to have pressure applied to the oppositely disposed end faces thereof through pressureoperated devices so that it may be bent about its longitudinal axis.

PATENTEUAUGIYIBYI 3.599.468

SHEET 1 [IF 2 FIG! IN VEI IT )R L U (Ll E N DI 0 L0 T METHOD OF AND APPARATUS FOR BENDING THE BACKING-UP ROLLS OF FOUR-HIGH ROLLING MILLS AND THE WORK ROLLS OF TWO-HIGH ROLLING MILLS This invention relates to further improvements in the method and apparatus for bending the backing-up or supporting rolls of four-high rolling mills such as shown in my earlier copending patent application Ser. No. 475,709, filed July 29, 1965, and entitled Improvements in Rolling Mills," and now U.S. Pat. No. 3,442,109.

Considerable difficulties have been experienced in maintaining the thickness of metal sheets and strips which are processed in a rolling mill to their nominal value, although this constitutes one of the essential qualities required of an apparatus of this type.

Although it is now relatively easy to obtain a constant thickness longitudinally of a sheet or strip, that is, parallel to the rolled direction, the same is not always possible as to the thickness of a section of the sheet in the transverse direction, that is, parallel to the axis of the rolls. in fact, heretofore unforeseen and relatively considerable fluctuations in the surface of the sheet or strip have been frequent and difficult to avoid.

lndependently of the thickness variations mentioned, it has also been found that undulations appear on the edges or at the center of the product during rolling.

To obviate these various disadvantages, it has been proposed to vary the balancing pressure which is exerted on the work rolls, but the results obtained are uncertainand of limited extent, especially where the table width of the rolling mill is considerable.

lnthe patent application referred to applicant has described an apparatus for bending the backing-up rolls in a multiroll rolling mill. According to that invention, pressure is applied to the journals of the backing-up rolls of the rolling mill thus interposing between the two chocks of the roll a system for compensating for the original convexity given to the roll, said system comprising at the work table side a compression bar braced between the two chocks and, at the opposite side, a tension bar, for example, a link, the length of which is ad justable during operation with the tension bar being articulated between the two chocks.

This organization involves using mechanical devices which necessitate substantially lengthening the cylinders and their neck portions so that they can support the various elements which are to transmit the useful forces produced.

Besides the aforesaid condition, the use of mechanical compensating means also results in the occurrence of friction which is sometimes very considerable between fixed and rotating parts which is manifestly highly undesirable since considerable pressures occur in the case of rolling mills of this type.

The present invention relates-to a method and apparatus for bending rolls, aiming at achieving the same object as the aforesaid application, the mans used, however, being in this instance essentially hydraulic with the force being applied not on the chocks to be then transmitted to the journals of the roll in question, but rather directly into the end wall of the roll journals. However, as in the previous application, applicant is very concerned to use only horizontal forces in the apparatus according to the invention, so s not to cause any disturbance to the system of vertical rolling forces, nor to modify the balance and the distribution of the stresses existing in the uprights of the rolling mill housing.

The forces produced by the apparatus according to the invention act on the end faces or walls of the journals concerned which permits inter alia of dispensing with using rolls of considerable length, traditional rolls being sufficient in this event, on the sole condition that the faces in question are correctly trued and carefully polished.

This advantage is all the more no notable since the most ad- I vantageous uses of the method of bending the backing-up rolls concern in fact large rolling mills using high pressures and, consequently, very heavy rolls.

According to one feature of the invention applied by way of nonlimitative example to a four-high rolling mill, a rigid abutment constituting a supporting member is arranged terminally and opposite each end of the two journals of a backing-up roll of the rolling mill, the two abutments corresponding to one and the same roll being connected by a certain number of connecting rods forming ties which may extend, along the roll in question, from one end of the mill to the other. The said connecting rods are supported locally by suitable means fast with the housing of the mill, for example, extending through bores formed for this purpose in the uprights of the housing,

On each of the aforesaid abutments there is arranged a system comprising one or more jacks which is adapted to act from the outside toward the inside in the axial direction of the supporting roll. The arrangement of the bearing points of these various jacks is such that they are distributed approximately uniformly over a parallel surface equal to that of the end cross section of each of the roll journals concerned.

Between each of these jacks and the end wall of the journal opposite it there are interposed one: or more intermediate bearing member, each of which comprises at its face directed towards the journal, a compartment filled with a fluid under pressure, which thus forms a cushion bearing against the journal.

Owing to the action of the pressure-operated jacks, adding to that of the fluid under pressure of the bearing cushion, the latter is applied firmly against the end face of the journal with which it is in contact and transmits thereto the entire resulting compressive force.

It will thus be seen that the working rolls are subjected by the assembly, constituted by the two bearing systems which enclose it, the action of which is on a common axis, to a compressive stress which can be regarded as preloading and which contributes to limiting pure bending stresses normally acting on the particular roll.

The foregoing applies more especially to the portion of the roll which is situated at that side of the neutral axis of the roll where the fibers of the metal undergo tensile stresses resulting from the bending of the cylinder. At the opposite side of the neutral axis thereof according to this invention, the metal fibers are subjected to compressive stresses which makes it possible to substantially reduce the additional compression to be provided by the apparatus. In fact, it can be considered that the points subjected to the additional compression and situated within said compressed zone of the journal constitute as many bearing points against which the compensating system assembly is braced in order to produce the desired preloading forces in the opposite portion of the journal and therefore of the roll.

Leaving aside the reactions in the ties, the action, on a cross section of the roll, of the compensating apparatus assembly can thus be summed up as a very high compression acting on the portion of the said section initially subjected to extension, the said compression being accompanied by a thrust reaction, which also results in a compression, in the remaining portion of the said secton, the latter compression, however, being of much lower value.

In a four-high rolling mill, the two backing-up rolls are both equipped with an apparatus according to the invention, making it possible to double the resulting compensating force, this force being considered in he vertical working plane of the machine. In this same vertical plane, the maximum spacing between backing-up rolls may be four times the spacing between the extreme bent position of a single roll, relatively to the position before deformation of said roll.

Other objects and advantages will become apparent from the following description taken in conjunction with the accompanying drawing, in which:

FIG. 1 is a partial view through a portion of one rolling mill stand showing the neck of a roll in elevation and the inventive concept shown in cross section positioned at the end thereof;

FIG. 2 is a view on line ll ll of FIG. l; and

FIG. 3 is, a fragmentary view of the entire width of the rolling mill showing a portion of the stands in elevation with the pressure applying mans onlthe left in cross section and those at the right shown in elevation.

Turning now to the drawing, there is shown in FIG. 1 only a portion of one side of a four-high rolling mill with the elements constituting the invention shown in detail. V

7 At 1 there is designated one of the uprights of the rolling mill housing, with 2 being the chock in which the journal 3 of a rolling mill roll is accommodated. The smooth, highly polished end wall or face of the journal is indicated at 4.

As will already be understood from the description, the elements shown in FIG. 1 areduplic'ated at the opposite end of the rolling mill with the abutments 9 (one shown) being positioned outboard of each end wall of the journal and held fast by means of the ties which are appropriately threaded and held by means of nuts 16.

The two bearing members 5, of substantially semicircular form (FIG. 2) are identical to one another and each comprises in the region of the face of the corresponding journal a compartment 6, the internal contour of which corresponds to the shape of the member, the compartment 6 being intended to be filled with a fluid under pressure, thus forming a bearing cushion against the end face 4 of the roll.

The pushing jacks 12 have their cylinder portions formed from boresprovided in one wall of the abutment member 9, the cylinders being constituted, for example, by cylindrical cavities indicated at 10. At 12 is designated the piston of one of these jacks in its working position with the driving fluid entering the working chamber 11 through ducts 17 and 21 which i are connected to one another by means of the port 23,. To prevent leakage, a sealing element 14 is seated in a channel in the cylinder wall and the piston 12 terminates at its front portion in a convex end or surface 13 made of a strong, treated metal which bears against the lining or insert member 8 fitted for this purpose in a seat in bearing member 5.

At 7 there is shown the fluid pressure duct which communicates wit the flexible pipe 22 that extends from the duct 21 and thus is adapted to supply the fluid cushion 6. Pipe 17, on the other hand, with which branch 21 is connected, ends in a joint 19 which holds the end of pipe 20, which is the feed pipe for the whole system.

Element 9 comprises two guides 18 positioned on both sides of bearing members 5.

A cylindrical casing 24, integral with element 9, surrounds the support elements unit as well as the chock cover, sealing being provided by a joint 25. This casing collects possibly occurring leakages, a pipe 26 conveying such leakages to a recovery tank not shown.

Numeral 27 indicates a shaft for centering and guiding element 9, which shaft is integral with the cover of the journal.

In the case shown in the figures, considering the fact that fluid cushion 6 and the two operating chambers 10 of the corresponding jacks are fed at the same pressure, the operation of the device depends on the fact that the sum of the transverse surfaces of the two operating chambers 10 is greater than the transverse surface of fluid cushion 6. In fact, only when this one condition is fulfilled can leakages at the junction between bearing members 5 and the end of the journal against which they rest be avoided.

The two jacks, located above the shaft of the roll, are fed simultaneously and therefore act jointly. The two jacks,

located below the shaft of the same roll are likewise fed together but at reduced pressure which is however sufficient to maintain, due to the difference, already mentioned, in the surfaces, the seal for the corresponding fluid cushion.

- ture of the cylinder which is related to it can be irected upward or downward. It is therefore sufficient to admit in one embodiment the control fluid at high pressure into the portion of the apparatus that acts upon the lower half of the transverse section of the cylinder. In another embodiment, the said fluid is admitted into the other portion of the apparatus. In each case the fluid is admitted at low pressure into the jacks which are not fed at full pressure.

In the preceding, the application of the invention to fourhigh rolling mills has been described. It is clear that the same apparatus can be applied in the same manner to two-high rolling mills.

That which I claim is:

1. In a rolling mill, a housing, a pair of working rolls, a pair of chocks for each of said rolls slidably mounted in suitable openings provided in said housing and at least one supporting roll for each of said working rolls, one at least of said rolls having necks extending from the ends thereof terminating in end walls, abutment means in spaced relation to each of said end walls, means connecting said abutment means with each other through the housing to provide a rigid assembly, bearing means in contact with each of said end walls, and plural pressure-responsive jack means interposed between said abutment means and said bearing means for imposing upon the end walls of said roll a contour-controlling bending moment by the application of pressure to said jack means.

2 In a rolling mill as claimed in claim 1, wherein the jack means and the bearing means are subjected to fluid pressure from a single source of pressure.

3. In a rolling mill as claimed in claim 2, wherein fluid pressure is introduced into selected ones of said jack means to bend the working rolls in a predetermined direction.

4. In a rolling mill as claimed in claim 1, wherein the jack means are positioned in bores provided in the abutment means.

5. In a rolling mill as claimed in claim 1, wherein the jack means are provided with offstanding means adapted to engage said bearing means.

6. In a rolling mill as claimed in claim 2, wherein the bearing means are provided with cushion means adapted to be subjected to fluid pressure.

7. In a rolling mill as claimed in claim 1, wherein the jack means and the bearing means are positioned in a sealed housmg.

8. In a rolling mill as claimed in claim 1, wherein the abutment means are provided with means adapted to cooperate with means associated with the necks of said working rolls.

9. In a rolling mill as claimed in claim 8, wherein the bearing means comprise semicircular members which straddle the mans provided on said abutment. 

1. In a rolling mill, a housing, a pair of working rolls, a pair of chocks for each of said rolls slidably mounted in suitable openings provided in said housing and at least one supporting roll for each of said working rolls, one at least of said rolls having necks extending from the ends thereof terminating in end walls, abutment means in spaced relation to each of said end walls, means connecting said abutment means with each other through the housing to provide a rigid assembly, bearing means in contact with each of said end walls, and plural pressureresponsive jack means interposed between said abutment means and said bearing means for imposing upon the end walls of said roll a contour-controlling bending moment by the application of pressure to said jack means. CM,2Rolling mill as claimed in claim 1, wherein the jack means and the bearing means are subjected to fluid pressure from a single source of pressure.
 3. In a rolling mill as claimed in claim 2, wherein fluid pressure is introduced into selected ones of said jack means to bend the working rolls in a predetermined direction.
 4. In a rolling mill as claimed in claim 1, wherein the jack means are positioned in bores provided in the abutment means.
 5. In a rolling mill as claimed in claim 1, wherein the jack means are provided with offstanding means adapted to engage said bearing means.
 6. In a rolling mill as claimed in claim 2, wherein the bearing means are provided with cushion means adapted to be subjected to fluid pressure.
 7. In a rolling mill as claimed in claim 1, wherein the jack means and the bearing means are positioned in a sealed housing.
 8. In a rolling mill as claimed in claim 1, wherein the abutment means are provided with means adapted to cooperate with means associated with the necks of said working rolls.
 9. In a rolling mill as claimed in claim 8, wherein the bearing means comprise semicircular members which straddle the means provided on said abutment. 